1. Field of the Invention
The present invention relates to a motorcycle. Particularly, the present invention relates to a mounting structure of devices incorporated into the motorcycle, such as an ABS unit, a canister, and a battery.
2. Description of the Related Art
Conventionally, in a vehicle body frame of a motorcycle, a pivot frame unit extending downward is typically coupled to a rear end of a main frame unit extending rearward and obliquely downward from a head pipe. Typically, below the main frame unit, an engine, a transmission, and others are laid out. Therefore, the main frame unit is commonly composed of a pair of right and left main frame members which are spaced apart from each other. For example, Japanese Laid-Open Patent Application Publication No. 2010-058763 discloses a motorcycle in which a pipe frame is composed of a pair of right and left pipes extending from a head pipe to a location near a rear end portion of a vehicle body, and a cross pipe coupling them together in a suitable location.
Rear arm brackets (pivot frame unit) are welded to the right and left pipes of the pipe frame, respectively, such that the rear arm brackets extend downward from substantially center portions of the right and left pipes in a forward and rearward direction. Pivots are attached to the rear arm brackets, respectively, and front ends of rear arms (swing arms) are supported by the pivots such that the rear arms are pivotable around the pivots. A rear frame unit is constructed in such a manner that rear ends of back-stays extending rearward and obliquely upward from portions of the right and left rear arm brackets are welded to the rear ends of the right and left pipes of the pipe frame, respectively.
In recent years, to improve safety, to meet emission regulation, etc., devices incorporated into a motorcycle, for example, an ABS unit, a GPS unit, and a canister of an evaporative fuel, have been increasing in number. Therefore, attention has been paid to a space in which these devices are laid out. For example, Japanese Laid-Open Patent Application Publication No. 2009-292350 discloses a mounting structure for laying out an ABS unit between and slightly behind right and left rear arm brackets, in a motorcycle including a pipe frame similar to the pipe frame disclosed in the Patent Publication stated above.
However, in a case where the ABS unit is laid out near the right and left rear arm brackets as in the latter conventional example, pipes, stays, and others constituting a vehicle body frame, such as the right and left pipes of the pipe frame, the rear arm brackets, a cross pipe, and back-stays, surround the ABS unit from above and from right and left sides. Therefore, it is very difficult to mount the ABS unit to the vehicle body.
To be specific, when the ABS unit is laid out in a space between the pipes and others surrounding the ABS unit, and bolts and nuts are tightened, interference with the surrounding pipes and others tends to occur. In addition, when a brake pipe is attached to the ABS unit mounted in this way, interference with the pipes and others is unavoidable. Furthermore, since a metal-made pipe must be drawn to outside the pipes and the like of the frame, its length tends to be great, assembling work becomes difficult and inefficient, and manufacturing cost increases.
Since the plurality of pipes and the like are combined three-dimensionally to provide a stiffness of the overall frame, it is very difficult to modify the layout of the pipes to widen a mounting space for the devices. Thus, in principle, it is necessary to ensure the mounting space between determined pipe works. If the pipes and the like are provided with a dented portion or a hollow portion to avoid interference with the devices, their stiffness may possibly decrease significantly due to concentration of stress.
In general, a dimension of the space between determined pipe works does not conform to an outer dimension of the device. When the device is laid out in this space, wasted space tends to increase. With an increase in the number of the devices, a vehicle width will inevitably increase. If this happens near a seat, a rider cannot fit leg portions to the seat suitably, and cannot attain unity with the motorcycle. Furthermore, it is difficult to ensure a substantial thickness of the seat depending on a balance with the height of the seat. That is, it is difficult to allow a rider to put the rider's feet on the ground comfortably while sitting on the seat comfortably.